Electric furnace.



No. 826,962. PATENTED JULY 24, 1906. B. PLATSCHIGK.

ELECTRIC FURNACE APPLICATION FILED NOV. 27. 1905..

PATENT QFFTQE.

BENVENUTO PLATSCHIOK, OF PARIS, FRANCE.

ELEQTRIG FURNAGE.

no. access,

Specification of Letters Batent.

Application filed November 27, 1905. Elerial No. 282.25%.

To all! whom, it may concern:

Be it known that I, BENVENUTO PLATS- CHICK, purveyor to the dentist trade, a subject of the King of Italy, residing at 3 and 8 Rue Ventadour, Paris, in the Republic of France, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This nvention relates to electric furnaces of the kind now in use in dentistry and other similar applications, in enameling, in chemistry, in bacteriolog &c.

Pleretofore in apparatuses of this kindthe muflle, its casing, and the electric devices form a whole, which in practice is difficult to take to pieces on the spot when, for instance, a muffle is to be replaced or repaired. When the furnace comprises an electric pyrometer, it is more particularly impossible to make repairs on the spot by reason of the difficulties attending the regulation of the indications of the said instrument, whereby the furnace can no longer be used for'the time being whenever the muffle has to be either replaced or repaired and the whole apparatus haste be sent back to the manufacturer.

The invention has for its object to do away with this inconvenience and to realize a great saving of time and money when electric furnaces of the specified kind have to be repaired. I

It consists, broadly, in rendering the muflie easily detachable from its casing and from the electric wires which connect it with the source of heating-current and also from the apparatus for measuring the temperatures should there be one.=- i

More particularly, the invention also consists in combining in the muflie itself with the thermo-electric couple, which is usually constituted by different alloys based on 'platina, suitable resistances so adjusted as to compensate for the differences which may exist between the electric and thermic constants of divers couples of the same make by reason of the irregularity of the alloys. Thisarrangement allows of delivering over to the trade muffies which are interchangeable-that is, all the couples present between their terminals the same thermo electric constants, and which consequently all give in connection with one and the same galvanometer the same pyrometric indications when they are subjected to equal temperatures. The necessity of a fresh stan'darding or of'a particular adjustment when a mufile has to be replacd is thus avoided, the result being a great saving i of time and money.

The accompanying drawings show, by way of example, one embodiment of this invention. Figures 1, 2, and 3 are respectively a front, a side, and a rear elevation of an electric furnace comprising an electric pyrometer. Figs. 4. and 5 are vertical sections on the lines A A and B B, respectively, of Figs. 1 and 2. Fig. 6 shows how the muflle is inserted in the furnace.

The muffle 1, of suitable fireproof'material, is provided with a metal jacket 2 and lies freely in a sheet-metal casing which may be opened at will. The said casing comprises a fixed portion, composed of a bottom 3, of a front wall 4, of a lateral wall 5, and of a rear wall 6, as well as amovable portion, composed of a lateral wall 7, with a rear extension 8 and an upper wall or lid 9.

The furnace is supported on legs 10 above a bed-plate 11, under which a rheostat may be arranged in the usual manner.

On the wall 4, provided with an opening 12, is pivoted the door 13, which serves to close the muffle. slideways 14 for the .two contact pieces 15, which are'fitted in the mufile and to which lead the ends of the platina wire 16, which serves to heat the said muflie.

Patented July 2c, 1906.,

In the wall 5 are out two vertical The wall 7 is hinged at 17 to the bottom 3, and the lid 9 is hinged at 18 to the wall 7,

so that these arts may be moved down on one side of t e apparatus, thus providing for-the easy insertion or removal of the muffie, as shown in Fig. 6. When the lid 9 is placed above the mufile, it may be secured to the -wall',5 by means of a rod 19, slidable through the rolled portions 20 and 21 of the walls 5 and 9. In the rear wall of the muifle is provided a .housin 22 for the thermo-electrio couple 23 and w 'ch is filled with asbestos 24. The inner end of the couple rojects into the chamber of the muffle, and t e outer ends of its branches are flush with or in a heat-repelling mass 25, located between the rear wall of the mufile and the jacket of the latter. by rods of different allo s of platina lead resistance-wires 26, whic extend to rods or pins 27, secured by sealin or otherwise on the muffle and carried bac Ward. The por- From the said branches constituted tions 6 and 8 of the casing are so cut as to allow the said rods to pass freely. On the bedplate 11 are secured two flat springs 28, soarranged as to bear against the contact-pieces 15, and two small columns 29, designed to receive the rods 27. i

To use the furnace thus fitted up, the springs 28 are Connected to the poles of a source of current so as to cause a suitable current to pass into the contacts and the heating-Wire 16. The small columns 29 are connected to a suitable galvanometer, showing the 'temperature'to whichis subjected the inner end of the thermo-electric couple 23.

In case the muflle requires to be replaced its casing is opened and the mufiie is lifted out by means of the ring 30 after having simply loosened thescrews 31, which hold the rods 27 on the small columns 29. Then a new muffle is put in place, the screws 31 are tightened, the casing is closed, and the furnace is again ready for operation. Furthermore, in order that a muflie may be substituted for another one without the accuracy of the indications of the galvanometer or other measuring apparatus being influenced in any Way all that is required when the muffle's are being made is that the resistances 26 shall be carefully regulated with respect to the thermo-electric value of the couples 23 with which they are combined. The muffles can therefore be henceforth easily, readily, and cheaply replaced on the spot.

It is to be understood that the inventionis not limited to the embodiment shown and described, as the arrangements may be varied at will without departing from the spirit ,of the invention, the essential feature being that the casing shall be so fitted as to allow of the electric connections ofthe' muffle being easily connected and disconnected.

I claim 1'. An electric muflie comprising a recipient of fireproof material, a heating-conductor secured in the wall of the recipient, two contact pieces projecting from the lateral face of the recipient and connected to the said conductor, a bed-- late, a casing on the bed-plate to receive t e said recipient, the

said casing having apertures in one wall for the passage of the contact-pieces, and springcontacts on the bed-plate to engage the said contact-pieces.

2. In an electric muffle, the combination of a recipient of fireproof material, a casing for the said recipient, the said casing havinga ance-wires aiainst the influence of the ternperature at t e outside of the apparatus and rods connected to the resistanrewires and projecting outside the recipient.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

BENVENUTO PLATSCHICK.

Witnesses:

HANSON C. Coxn, MAURICE Rover. 

